import java.sql.*;

public class Hello {

    // psvm
    public static void main(String[] args) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        // jdbc 步骤
        // 1、加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2、创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");


            // 3、写sql
            String sql = "select * from user3";

            // 4、预编译sql
            preparedStatement = connection.prepareStatement(sql);

            // 5、执行sql
            resultSet = preparedStatement.executeQuery();

            // 6、遍历结果
            while(resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString(2);
                String pass = resultSet.getString(3);
                System.out.println(id+"----"+name+"----"+pass);
            }

        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            // 7、关闭资源
            try {
                if(resultSet != null){
                    resultSet.close();
                }
                if(preparedStatement != null){
                    preparedStatement.close();
                }
                if(connection != null){
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }

        }

    }
}
